To satisfy an ever-increasing demand for computing and data processing power both with respect to processing speed and storage capacity, computer design has been evolving toward increasingly compact arrangements of components and assemblies. Attention has been directed to the number of so-called package levels (a package being defined as a group of structurally similar components or assemblies) as, e.g., by R. F. Bonner et al., "Advanced Printed-Circuit Board Design for High-Performance Computer Applications," IBM Journal of Research and Development, Vol. 26, No. 3, May 1982, pp. 297-305.
Attention has also been given to the way components and assemblies are interconnected; e.g., C. W. Ho et al., "The Thin-Film Module as a High-Performance Semiconductor Package," IBM Journal of Research and Development, Vol. 26, No. 3, May 1982, pp. 287-296, discuss a multi-chip module of silicon chips attached to thin-film transmission lines. Among early proposals for the achievement of high device density in silicon technology is one by P. Kraynak et al., "Wafer-Chip Assembly for Large-Scale Integration," IEEE Transactions on Electron Devices, Vol. ED-15, No. 9, September 1968, pp. 660-663, where silicon chips are bonded "face down" on a silicon wafer.